Method of molding perforated elastic material



June 27, 1944. J. A. IIGRABEC METHOD OF MOLDING PERFORATED ELASTIC MATERIAL 7 Sheets-Sheet l [live/2101'.

By Zi g Filed Sept. 15 1937 wsN Hider/zap June 27, 1944. J. A. GRABEC METHOD OF MOLDING PERFORATED ELASTIC MATERIAL Filed-Sept. 15, 1937 "r Shets-Sheef. 2 3 v v w N N 'J'. A. GRABEC METHOD or" momma PERFORA'I'ED ms'nc MATERI'AL June 27, 1944.

Filedfiept. 13, 193? 7 Sheets-Sheet 3 Inue/zior;

fliiorneys June 27, 1944, J, A, GRABEC 2,352,194

, METHOD OF MOLDING- PERFORATED ELASTIC MATERIAL Filed Sept. 13, 1957 7 Sheets-Sheet 5 Inuezziar:

Patented June 27, 19

Mrs

marnop or Momma rnarcaa'rsa s'rrc irra'rsamr.

Application September 13, 1937, Serial No. 163,602

(Cl. ll2) 2 Claims.

This invention relates to a novel method and apparatus for producing foraminous, elastic sheet material.

More particularly, the present invention is a continuation in part of my copending applications, Serial No. 709,607, filed February 3, 1934, and Serial No. 24,943, filed June 4, 1935, both of which relate to materials that are manufactured according to the present invention. I

Rubber, or rubberized materials are used for all manner of garments, but inasmuch as my new materials, although well suited for general uses, are particularly adapted to corsets and girdles, I shall, for the sake of brevity, refer to such garments as corseting materials.

Previously, rubber corseting materials have been made by punching apertures either in a sheet of rubber or in a-sheet of combined fabric and rubber. The products have not been satisfactory for punched sheet rubber tears easily and the relatively few holes in the sheet have been wholly 'insumcient to permit transpiration from the body. Consequently, rubber corseting materials have been hot, uncomfortable and frequently irritate the skin.

In contradistinction to these' perforated or punctured materials, my improved material possesses an open, regular gauze-like structure. It is light, strong and open textured, permits free transpiration and is well suited for use in bathing suitsor corsets; I I

It is the primary aim and object of the present invention to devise a method and apparatus for obtaining a composite sheet material, composed of an elastic material, such as rubber, and of a backing material,-such as distensible textile fabric, which requires no adhesive, which is of light weight, well ventilated, and permits transpiration, 'and which has good distensibility in any direc- It is a more particular object of the present invention to devise a method and apparatus for molding sheets of an elastic material, such as rubber, and distensible textile fabric, into a composite material in which the two materials are intimately united and in which substantially all of the elastic material has been molded into a new form. which not only gives a maximum distensibility to the composite material with the least amount of elastic material, but also provides for effective ventilation and complete transpiration wherever worn.

It is another particular object of the present invention to devise a method and apparatus for molding the elastic stock material of the compcsite material into such a form that-the composite material is particularly suited for holding stitches when sewn.

It is another object of the present invention to devise a method and apparatus for molding elastic sheet material, such as rubber, into a new form. in which it is given excellent distenslbility, is well ventilated, and is very light in weight.

Before explaning in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and. of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

In said drawings:

Fig. 1 is a cross-section through a machine in which materials may be produced according to the present method.

Fig. 2 is a longitudinal section of the machine, taken substantially along the line 2-2 of Fig. 1.

Fig. 3 is an enlarged, fragmentary section of the two supply materials which are to be molded into a composite material in the present machine.

Figf 4 is a cross-section of the machine illustrated in Figs. 1 and 2, and of other structur which may be used in conjunction with said machine.

Fig. 5 is an enlarged, fragmentary section of three supply materials which may be molded into a composite material in the present machine.

Fig. 6 is a fragmentary view of an element of the machine, to wit, a pin roll.

Fig. '7 is a fragmentary view, partly in section,

. sions of the teeth of said "pin roll.

Figs. 12 to 1'7, inclusive, are enlarged, fragmentary perspective views, partly in section, of certain forms which the teeth of the pin roll may assume.

Figs. 18 and 19 are greatly enlarged, fragmentary sections of the cooperating molding structure of the machine which includes the "pin roll. More particularly, these figures disclose different shapes of the teeth of the pin roll.

Fig. 20 is an-enlarged, fragmentary plan view of one form of composite material that may be produced in the present machine.

Figs. 21 and 22 are fragmentary sections on the lines 2I2I and 22-22, respectively, of Fig. 20.

Fig. 23 is a greatly enlarged, fragmentary sec tion of cooperating structure of the machine for molding only elastic material without any backing material such as fabric.

Fig. 24 is an. enlarged, fragmentary section through material produced by the cooperating structure shown in Fig. 23.

Fig. 25 is an enlarged, fragmentary section through the same material as shown in Fig. 25 which is, however, backed with fabric.

Fig. 26 is a fragmentary section through a modified construction of one of the elements of the present machine, .to. wit, a counter" roll which cooperates with the pin roll.

Fig. 2'7 is a fragmentary plan view of one element of a modified form of mold for producing the same material as in the machine disclosed in Figs. 1 and 2.

Fig. 28 is a section taken substantially along the line 28-23 of Fig. 27, showing also the other element of said modified mold in section.

A preferred embodiment of my machine, adapted for continuous production is illustrated in Figs. 1 and-2.

General construction 0) machine The machine is mounted on any suitable base 3i and comprises a main frame which may consist of a number of suitably joined structural steel shapes. More particularly, suitably supported, spaced uprights 32 and 34, joined at the top by aremovable tie bar 36, provide two opposite, vertical guides for three pairs of bearing blocks 33, 40 and 42 which rotatably support rolls 44, 46 and 43 respectively. These rolls 44, 48 and 43 are provided with annular shoulders 50, 32 and 54, respectively, which engage the adjacent bearing blocks 33, 40 and 42 respectively,

' to prevent the axial movement of said rolls.

Mounted in any suitable manner on one of the channel irons 56 of the supporting frame of the machine are several spaced bearing brackets 58 which rotatably support a shaft 60, provided with two spaced worms 62. The worms 62 are in permanent mesh with worm gears 64,'mounted Figs. 29 and are charts which graphically illustrate two examples of temperature and plasticity conditions of the rubber stock of the material prevailing shortly before, during and 'im- 'mediately after the molding process. These charts show also the degree of vulcanization of the rubber stock in relation to its temperature and plasticity conditions.

In accordance with the present invention, a layer or ply of uncured rubber stock, which may be superposed upon a layer of distensible textile fabric, is molded into a perforated pattern by two cooperating pressure-mold members, one of which includes a multiplicity of perforating elements and the other of which provides a surface of slightly yieldable material in the indentations of which the tips of said perforating elements become seated. In order to mold the uncured rubber ply into a perforated pattern, and also firmly unite the same with a layer of textile fabric if so desired, the rubber ply is heated until it reaches a moldable or pliable stage. The heated rubber ply is then molded under pressure between the bite or in the cavity of said mold memhers. If the rubber sheet is to have a backing on spaced vertical spindles 66 which are threaded at 68 and cooperate with internally threaded sleeves Iii, guided for vertical movement in cross bars 12 which are secured in any suitable manner to theuprights 32, 34. Also mounted on the spindles 66 are spaced collars I4 which straddle the opposite flanges I6 of several channel irons 13 of the supporting frame of the machine. Consequently, rotation of the worm gears 64 results in rotation of the spindles 65 but not in any axial movement thereof. The sleeves 10 are provided with heads 80 which are received in rematerial of textile fabric, the same is superposed on said rubber sheet whereby some rubber will also be molded into meshes of the textile fabric and establish a firm bond between the two materials. The cooperating pressure-mold mem-- bers may take the form of either cooperating dies or of two profiled rolls. The material obtained by the pressure mold in either form has a geo- I cesses 32 of the bearing blocks 33 and retained therein by ring members 34. The heads 30 of the sleeves III are preferably square or of other suitable shape so that said sleeves will not turn when the spindles 66 are rotated. One end of the worm-carrying shaft 60 is provided with a wheel I wherewith to manipulate the lowermost or "counter" roll 44 toward and away from the middle roll 43, as can be readily understood.

The middle or pin roll 46 has a fixed disposition inasmuch as its bearing blocks 40 are bolted or otherwise secured to the uprights 32, 34.

The uppermost roll 43 is supported in a manner similar to the counterroll 44 and is covered at 233 with a relatively soft and yieldable mate rial such as soft rubber. More particularly, the bearing blocks 42 receive the preferably square heads 38 of two sleeves 90 which are internally threaded at 32 to receive threaded spindles 34 on which are mounted worm gears 98, bearing with their hubs IllIi against brackets I02, bolted or otherwise secured to the tie bar 38. The sleeves 30 are guided for vertical movement in the tie bar 36. Also mounted on the spindles 34 are collars I03 which are in engagement with the brackets III2 and, together with the hubs- I03 of the worm gears 33, prevent axial movement of said. spindles l4.- Permanently meshing with the worm gears 33 are worms I08 which are'provided on a shaft IIO, journalled in spaced bearing brackets II2 which are mounted on the tie bar 36. Mounted on one end of the shaft Ill is a wheel II4 for. manipulating the the surface of one of the mold members. The

molded material is then vulcanized so that it will thereafter permanentlyretain its form.

uppermost roll 43 toward-and away from the pin roll L The middle roll 4! is provided with an extension III which has mounted thereon a comparatively small spur gear 3 and a large worm gear I23, the latter being in permanent mesh with a worm 922 on the slow shaft I23 of any conventional reduction gearing lid-the fast shaft of said reduction gearing is coupled'in any con' venient manner to the shaft of-an electric motor i223, suitably mounted on the-machine base 36. Any other drive may, of course, be'used for the middle roll The rolls Q 3, and 48 carry identical gears iii-t3, i3? and 93 3, respectively, which are keyed or otherwise secured to. said rolls at ltd. These gears Kid, 63% and 834 are preferably of the herringbone type to obviate any relative mot'ion therebetween, and are adapted to drive the rolls tit and 63 from th'e'pin roll 38 whenever the'former are in such proximity to the roll d6 that their gears i853, it, come to mesh with the gear-132;

The rolls 3Q, 65 and 58 are centrally recessed at I38, i at and M2, respectively, to form steam chambers which are closed at their'open' ends by stuffing boxes Mt through which extend steam delivery pipes Hid, having inlets Hill which are in communication with manually operable valves (not shown) for the admission of steam to said pipes from any convenient source. A rod it? extends through the rolls dd, 25 and till which counteracts any tendency of the steam pipes its to turnwith the stufilng boxes I when the rolls M, 63 and $8 rotate.

It will be observed in Fig. 2 that the steam pipes i 33 extend nearly-to the ends'ihfi of the steam chambers in the rolls 5%, 68 and 6% so that steam discharged from the pipes flows throughout the greater length of the steam chambers in the rolls before escaping through the outlets H2 and from thence to a waste line (not shown). Of course, any medium'other than steam may be used for heating-the rolls flt; t6 and E8. 5"

Bolted or otherwise secured at' idil to two of the uprights 8, 3 oi the machine-frame are spaced bearing brackets iii; which rotatably support at H58 a core 9%, preferably in the manner shown in Fig.1 to facilitate removal of said core. Wound on this core is a supply I62 of material. consisting of two superposed separate layers or plies i555 of rubber and N6 of dlstensibl textile fabric; A string or cord I58, secured with one end at lid to one its other end, may be passed over the core ltd to exert a sufiiciently' large braking force on the supply roll H32 in order to'prevent the same from freely rotating. Evidently, an other well known construction may be used in braking the supply roll I62.

The same uprights 32, N which carry the bearing brackets ibt are provided with guides H4 in which are mounted two spaced, vertically adjustable frames lit, providing vertical guides lit for lower and upper bearing blocks 5% and IE6, respectively. The lower bearing blocks tilt,

' the same figure.

pression'of the springs Hill at will.

The lower roll 582 carries a gear 250 which is in permanent mesh with the earlier described spur gear M8 on the pin roll 56. This roll is. therefore, rotated in clockwise direction asviewed in Fig. 1, whenever the pin roll is rotated in its normal direction, indicated by the arrow 2% in The upper roll N38 is freely rotatable and rotates merelyby virtue of its frictional engagement with the finished mate= rial as it leaves the machine. For reasons to be explained hereafter, the ratio between the gears lit and Eli? is such that the peripheral speed of the roll M22 is somewhat greater than that of the pin roll 6b. The rolls W2 and 388 will hereafter be referred to as pull-0d" rolls.

Also mounted in any suitable manner on the uprights 32, 3d are two spacedbearing brackets the which rotatably support at 252 a core Edd, preferably in a manner similar to that illustrated in Fig. 1 to facilitate the removal of said core. Wound on the core 2% is a supply of a somewhat distensible fabric 235 which may be used in the machine aswill be hereafter explained. A similar braking device as the tensioned string ifiton the material supplyroll 552 may be applied to the roll 2% to prevent free rotation of the same. While the machine illustrated in Figs. 1, 2 and 4 shows a vertical disposition of the rolls to, as and at, it is to be understood that the same could be arranged in any other corrveriieritv manner, for instance, horizontally. Vertically disposed rolls such as shown in Figs. 1, 2 and i have, however, the advantages that foreign matter cannot drop'between thea-olls'and that the of the uprights 32. 33 and carrying a comparatively light" weight 612 at which normally rest by gravity on the bottom surfaces Hid of the guides I18, rotatably support a roll M32. The upper guide blocks iddrotatably support another roll I88 which normally. rests by gravity on the lower roll 152, but may be pressed against the latter by means of compression springs ltd which are interposed between the bearing blocks i" and yokes E92, slldable in the guides I18 of theirames H8. The rolls uez, 888 are preferably covered with a resilient, yieldable material, such as soft rubber.

Set screws let, received by cross bars I36 of the.

frames H8, bear against the yokes I92 and are operator of the machine may readily see thematerial pass'between the various rolls and quickly observe any faults in their cooperation due to any cause whatever.

Alternative construction of pin roll The pin roll 6% may be a steel roll 2% having the perforation-forming elements 'or teeth 2% 22%. The spiral and longitudinal machining. of

the steel blank 2% is also indicated in Fig. 6 by a few straight lines 221 and; 229, respectively.

Machining of the steel roll 22% as aforesaid produces orderly arranged teeth 22% which are square or at least rectangular in section along planescurved concentrically to the-periphery of the roll. Subsequent operations with a file, profile cutter 'or any other convenient tool may serve to round the flanks of the teeth substan-.

tially as illustrated in Figs. 12 to 15, inclusive, or to provide various tapered shoulders 235 in the flanks of the teeth as illustrated in Figs. 13 to 15, inclusive. The bottoms of the peripherally and longitudinally extending tooth cavities mayv be rounded during the spiral and longitudinal machining of the steel roll 2%, or they may be rounded subsequently to assume any desired curvature. By making the spiral and longitudinal grooves in the steel roll 220 of 'difierent depth, it is obvious that the tooth cavities periphorally and longitudinally of said roll will be of correspondingly different depth as shown in Fig. 8. The dlfierent depth of these tooth cavtties provided with handles 898 for changing the comcauses intersecting rubber ribs tohave diflferent heights. In so machining a steel roll. it is possible to obtain a very great number of teeth per square inch of the periphery of the roll.

If a considerably greater number of teeth per square inch of the periphery of the roll is desired, it is preferable to use the modified pin roll in Fig. 7. This pin roll comprises steel laminations 228, which are spaced from each other by interposed spacers 238 and stacked on a steel core 282. The core 232 is preferably provided with a shoulder 234 against which the laminations 228 and interposed spacers 230 are pressed by any suitable means such as the nuts 235, for instance.

Prior to the assembly of the laminations 228 with the spacers 230 and the steel core 282, said laminations are preferably stacked side by side and their peripheries machined to obtain teeth 288 of any of the profiles shown in Figs. 9 and 12 to'15, inclusive, if viewed in one direction, to

wit, longitudinally of the stacked laminations.

It is also possible to mold intersecting rubber ribs of different height, simply by radially spacing the bottoms of the machined toothcavities in the the laminations may, for example, be twisted relative to each other to any desired extent so that the teeth of one peripheral row project into the cavities between the teeth of an adjacent peripheral row if viewed longitudinally of the roll as illustrated in Fig. 10. Also, certain peripheral rows of teeth may without special cost be spaced at closer intervals than other peripheral rows of'teeth, or the teeth of certain rows may be made smaller than the teeth of other rows, all as indicated in Fig. 11. Consequently, the laminated pin roll has the advantage that irregular perforation patterns can be readily obtained without great cost. Also, if one or more of the perforating teeth of a laminated roll become excessively worn or even broken it is a simple matter to replace some laminations and use the same pin roll again.

It is to be understood that the alternative constructions of the pin roll are by no means limited to the described modes of machining either a blank steel roll or laminations, nor to the few illustrated possibilities of obtaining different perforation patterns with laminations, nor to the few illustrated forms of the teeth of either alternative construction of the pin roll. Obviously, shapes and profiles of the teeth other than those illustrated in the drawings may be found advantageous in certain cases.

Construction of counterroll The counterroll 44 (Figs. 1 and 2) has a peripheral element of softer material than the material of the teeth of the pin roll and must even be somewhat elastic to assure uniform seating of said teeth on said counterroll while the machine is in operation. For reasons which will appear obvious hereafter, the counterroll must also be able to transmit heat from its steam chamber I38 to its periphery. The steel core 240 of the counterroll 44 may, therefore, be covered with rubber 24! of relatively high durometer hardness or any other" suitable material such as paper, artificial resins, synthetic rubber, pressed wool or rags, or any of these materials combined with fabric or even tin or lead. The cover 2 is pref erably confined between an annular shoulder 242 of the steel core 2" and a threaded or shrunk collar 244 thereon. Consequently, if the cover material becomes softened when heated, it cannot spread beyond the ends of the core 248 but may expand radially only. Since substantially accurate register of the pin roll and the counterroll is always maintained, the tips 250 of the teeth of the pin roll work into the cover 2 of the counterroll, forming small indentations 25i therein. Continuous realignment 1 between the same teeth and the same indentations makes it imperative that the ratio between the gears in and I82 be an integer and that the diameters of the rolls 44, 46 be inversely proportional to the ratio of their gears I30 and I32, respectively. Also, micrometric" differences in the height of the teeth of the pin roll create micrometric differences in the depth of the corresponding indentations in the counterroll so that the load transmitted by each tooth to the counterroll, is the-same and. uneven wear of these teeth is effectively prevented.

The counterroll 44 may in some instances require a surface temperature of C. or more. At such a temperature, a cover material of hard rubber may become softened and, although the counterroll will continue to perform satisfactorily, the hard rubber cover 2 may loosen from its steel core 240'. Consequently, the counterroll shown in Fig. 26 is prefered when high temperatures are required.

This counterroll consists of a steel core 260 and paper laminations 282 which are packed against an annular shoulder 284 of said core 260 by nuts 266 or any other suitable means. Inasmuch as paper conducts heat very poorly, it is obvious that the width A (Fig. 26) of the paper laminations 262 should be kept as small as possible, yet permit a tight packing of the laminations on the core. Such a paper covered roll works well at temperature ranges above those practicable for rubber covered rolls.

Inspection device The finished material I65 may be passed over an inspection device 283 (Fig. 4) as it leaves the machine. This inspection device may comprise any suitable frame 281 on which is mounted a box-like structure 288, having at its top a transparent plate 288, such as glass, and housing a light socket 290 with suitable electrical connections and a lamp 292 in said socket for illuminating the composite material 282 from below as it passes over said inspection device. An operator may thus discern the. quality of the perforations in the rubber stock of the finished material. The use of this inspection device is naturally a matter of choice.

Vulcanizing box The finished material may also be passed through a vulcanizing box 284 (Fig. 4) as it leaves the machine, and thereafter guided to a wind-up roll 285 over a guide roll 286. The vulcanizing box 284 may comprise any suitable frame 294 which carries a box-like structure 296, having horizontally aligned inlet and outlet openings 298 and 888, respectively, through which the finished material passes. These openings may be lined with pieces 302 of mohair between which the finished material may pass without becoming damaged.

While passing through the vulcanizing box, the composite material rests on an endless conveyor or belt I04 which passes over suitably mounted guide rolls 806, 308 and ill and over combined guide and tensioning rolls 8l2. One of the guide s earer rolls, either 3% or bit, is driven inany suitable manner (not shown) however, preferably so that the endless conveyor moves at the same rate at which the finished material leaves the machine and is wound on the roll 285. The wind-up roll 285 may be driven in any suitable manner (not shown).

Any suitable heating means may be provided in -the box-like structure 295. In the present instance, there-is shown a steam coil ti l, having an inlet Sit and an outlet are. Steam from any suitable source (not shown) may be admitted to said steam coil 3M, preferably under the control of a manually operable valve (not shown).

Mode of operation of machine whereupon the counterroll it being preferably slightly withdrawn from the pin roll when the machine is at rest, is brought into re-engagement with the pin roll 36, while material from the supply roll l62 is at the same time held between the bite of both rolls id and 86. This supply material consists in the present case of the superposed layers let and its of rubber and distensible tex- 3 tile fabric, respectively, and is so fed between the rolls Ml, it that the rubber layer ltd is next to the pin roll. As best shown in Fig. 1, the material I64, I66 passes from the supply roll ltzto the counterroll til, then partly around the periphery of the latter until it meets the pin roll :36 on which it remains for some time, and is finally drawn from said pin roll by the pull-oft rolls i82, I883.

The supply material i6 3, its is heated by the counterroll 5% to such an extent that the rubber ply IE4 is plasticized when said supply material reaches the bite of the rolls it, 56 wherein the plastic rubber becomesmolded and thereby also.

firmly bound to the fabric layer its in a manner to be described in detail hereafter. The material,

which is now in composite form, is then'either cooled or further heated by the pin roll it while traveling with the same. Since it requires some force to withdraw the composite material from its engagement with the pins of the roll, the lower pull-oil roll I82 (Fig. 1) is driven at a greater peripheral speed than the pin roll se. The pull distends the material slightly and frees it from the pins. By urging pull-oil roll 6&8

against the lower roll E82 under the variable.

compression of the springs its, the operator may easily regulate the pull on the composite material !65 which is exerted by the rolls I82, its. In this way the composite material may be drawn from the pin roll it within a safe angular range.

Heating of rolls posite material 185 is to be vulcanized on the pin critical plasticity until its temperature reaches a. The rubber stool: is in contact with both rolls M, lit between the points (1, e and b, c oi the temperature and plasticity curves, respectively. Here, the flowing and molding of the rubber takes place. The rubber stock is finally heated by the pin roll which has a much'higher surface temperature than the counterroll as is evident from the course of the temperature curve in Fig. 29. The term "critical plasticity" as used herein and in the appended claims denotes that point in the plasticity curve at which the rubber stock can be removed from the pin roll without incurring plastic deformation: Removal of the composite material may, therefore, take place anywhere between the lines 9 and 12. since the plasticityof the rubber stock is now below the critical plasticity a. Complete vulcanization of the rubber stock on the pin roll is unnecessary. The remaining degree of cure (a to )2) may be given the stock in the vulcanizlng box 284 (Fig. 4)

Fig. shows curves similar to those of Fig. 29. These, however, illustrate the condition where the stock is vulcanized outside of the machine. The counteroll again heats the rubber stock well above the critical plasticity until its temperature reaches 1. The rubber stock is then in contact with rolls M and 45 between the points I, m and i, k of'the temperature and plasticity curves,

respectively, and the molding-Process takes place then. The rubber stockis finally cooled by the pin roll which has a considerably-lower surface temperature thanthe counter roll as is evidenced fromthe course of the temperature curve in Fig. 30. Removal of the composite material may then take place at the line 1: immediately after the plasticity of the rubber stock is below the critical plasticity a. No appreciable vulcanization of the rubber stock: has as yet taken place, and the same is subsequently vulcanized in the box 2nd (Fig. 4) for instance.

In order to expedite the cooling of the rubber stock and thereby quickly lower its plasticity I below critical so as to expedite the removal of roll 46 or whether the same is to be vulcanized Fig. 29 shows several curves which represent the temperature, plasticity and vulcanization degree of the rubber stock of the material when the same is to be vulcanized on'the pin roll. The

later, for instance in the vulcanizing box 28% (Fig. 4).

counterroll 45 heats the rubber stock above the s unvulcanized composite material from the pin roll, a, cooling medium is introduced into its chamber its instead of steam.

If it is desired to cover the rubber material on both sides with fabric, a sheet 281 of fabric from the supply roll 296 is also fed into the machine in the manner illustrated in Fig. 4. The uppermost roll it is then lowered and forced into eneasement with the pin roll 46 to such an extent that the soft cover see of the roll 48 forces the fabric Edi against the bottoms of the tooth cavities in the pin roll. Some steam may be admitted to the roll rate cause evaporation of any moisture in the fabric 2" before the same I Cooperating dies I Instead of using the described rolls for a continuous process of forming composite material,

the cooperating dies "0 and 342 (Figs. 27 and 28) may be used ior smaller articles-of a composite material which do not justify the higher cost of rolls. More particularly, the dies 340 and 342 are provided with dowel pins 344 and registering holes 346. Provided in the bottom die 342 by any suitable method are a number of perforating teeth 348 which may be of any suitable shape. The top die 34!! is provided with a lining 350 which may be of the same material as the cover material 2 of the counterroll 44 and be indented at 242 by the teeth 348 of the die 342.

A sheet of rubber with or without a superposed layer of fabric is placed in the dies, whereupon the latter are closed under pressure andheat is applied to the sheets through the dies. A molding process takes place then which is the same as thatin the rotary rolls. vulcanization of the molded material can. be completed in the dies by the application of heat for a suitable period, or the die can be cooled after the molding process is completed and the material removed therefrom for vulcanization elsewhere.

Molding process.

Figs. 18 and 19'illustrate the molding process which the rubber of the supply material undergoes either in the rolls 44, 46 or in the dies 340, 342. It will be observed in the above figures that the highly plastic rubber I64 is forced against the fabric I56 by the flanks of the, perforationmolding teeth, resulting in the formation of the intersecting rubber ribs 210 (Figs. 20 to 22). No threads are ever severed or broken, for the plastic rubber grips each thread and as it is being displaced by an intrusive molding tooth, each thread is carried away from the point itself. In addition, the wedging effect of the flanks of the adjacent molding teeth causesthe rubber not only to flow into and to assume the shape of the cavities between the adjacent teeth, but also the rubber is flowed into the meshes of the fabric to an extent illustrated by the stippled areas 212 in Figs. 18 and 19. Thus the rubber is molded about many threads and is securely bonded to the fabric.

By using the shouldered teeth shown in Figs. 19 and 13 to 15, inclusive, more rubber will be forced into the meshes of the fabric.

If it is desired to give the composite material a pleasing ribbed appearance on its fabric side, the surface portions 230 between adjacent indentations 25l may be rounded (Fig. 19). If a rubber sheet alone is molded, these rounded surface portions 280 will round theadiacent portions of the rubber ribs (Figs. 23 and 24).

Material thus molded may have the texture that is illustrated greatly enlarged in Fig. 20. Figs. 21 and 22 are greatly enlarged sectional views of the perforated material shown in Fig. 20. Now and then a few perforations are continued through the fabric wherever a perforating tooth has spread the meshes of the fabric apart. This is also shown in Figs. 21 and 22'.

The teeth 320, shown in perspective in Figs. 16 and 23, are particularly suited for forming very thin sheet rubber without fabric into a perforated material such as illustrated in Fig. 24. This. material comprises very fine, intersecting ribs 322.

If it is desired to apply a backing material 324 of any kind of fabric to the perforated rubber sheet in Fig. 24, the teeth 326, shown in Fig. 17, may be used. These teeth 326 may differ from the teeth 320 only by having tips 328 which will pass into the fabric 324 on molding the composite material 330 (Fig. 25). The tapered shoulders 332 of the teeth 326 will force some of the rubber into the meshes of the fabric and thus establish a lasting bond between both materials.

Distensibility of composite material Knit fabrics have little extensibility in the direction in which the goods are knitted, but possess extensibility in a direction at right angles thereto. However, corsets, girdles and similar articles require a material which is distensible in any direction. By stretching knit fabrics in the direction of their greatest extensibility and then permanently combining rubber therewith while the fabric is in a stretched condition, the composite material which results is distensible in any direction. This discovery is used to good advantage in the manufacture of the new composite material.

, Thus, the fabric material is held stretched in 'the direction of its greatest extensibility during the molding process. A continuous supply of textile fabric, which can be stretched lengthwise as it is fed into the machine, is obtained by severing knit textile fabrics across their width,

i. e., in the direction of their greatest extensibility and then sewing together the severed fabric pieces with their non-severed sides in end to end relation.

Rubber material In order to obtain a good product of composite materials or of rubber alone, the rubber must .be. tough and must have considerable distensibility and resistance against tearing. .A high grade product is, for instance, obtained by using the following rubber compound for the rubber ply: pale crepe rubber, 16% zinc oxide, 1% accelerator, 2% sulphur and 1% color. A product of somewhat poorer quality may be made, for instance, with the following rubber compound: 50% crepe rubber, 5% zinc oxide, stearic acid, 1% color, 40% whiting, 1% accelerator, 1% sulphur and 1%% softener. These are, of course, only examples of rubber compounds which can be used, and it is to be distinctly understood that any other rubber compounds may be used.

The terms elastic material," rubber or rubher-like substance, as used herein and in the appended claims, are meant to include any material or composition of matter having the property of elasticity and being capable of conversion from a deformable into a more or less permanently elastic state.

Characteristics of new materials .The textile fabric is firmly attached to a coherent system of molded ribs 210 of suitable breadth and height which are of elastic material, such as rubber. The height and cross-section of the ribs is determined by the desiredresistance of the finished or perforated material to distension. Also, if the resistance to distension in two transverse directions is to be different, the intersecting ribs of elastic material will be made of different height or of different cross-section, or both.

While a finished material of any desired perforation pattern may be produced, it is preferable to produce a finished material in which the uncovered area of the textile fabric used is as large as possible, and should preferably amount in all to at least 50% of the entire area of the fabric material are on the other hand preferably spaced as closely as possible since thick, widely spaced webs not only detract from the ventilating properties of the composite or finished material, but also reduce its suitability for holding stitches when sewn.

If the composite material is used for wear on the human body with the rubber side turned toward the skin, the contact area between the skin and the composite material is very small, due to the rounded peaks 2" (Figs. 21 and 22) of the rubber ribs 21$ as can bereadily understood. Consequently, very few pores will be covered by 1 rubber, and the greater area of the skin will be well ventilated so that the wearer will experience a welcome cooling effect wherever the material is worn it air has free access to said material.

The elimination of any excess rubber in'the composite material by the molding of a comparatively thin ply of rubber into intersecting ribs with intervening rectangular or squareperforations not only represents a saving in rubber stock, but results also in a composite material of light weight which has great elasticity in the directions of the intersecting rubber ribs.

1 claim:

1. The method of producing perforated sheet 7 rubber; which includes placing a sheet of uncured rubber on a heated backing surface to heat-plasticize the rubber forcing simultaneously a multiplicity of heated molding cores through the rubber sheet and against said backing surface substantially when the rubber-has become heat-plasticized, and maintaining the molded rubber in contact at least with the heated cores until at leasl such a degree of vulcanization has taken plac: that the rubber permanently retains its moldec shape. v

2. The method of producing foraminous composite material, which includes superposing a sheet of uncured rubber upon a sheet of textile fabric, placing the superposed sheets on a heated backing surface with the fabric lying on said surface to heat-plasticize the rubber, forcing simultaneously a multiplicity of heated molding cores through the rubber sheet and against saidsurface substantially when the rubber has become heat-plasticized, and maintaining the rubber and fabric in contact at least with the heated cores until at least such a degree of vulcanization has taken place that the rubber permanently retains its molded shape.

J A. GR ABEC. 

